RU2735839C1 - Method of producing sorbent for purification of waste water from nickel ions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to chemical engineering, particularly to production of a sorbent intended for use in the field of ecology for purification of water bodies, in particular, for purification of waste water from nickel ions by sorption. Present invention relates to a method of producing a sorbent for purifying waste water from nickel ions, which involves sludge drying and grinding. Sludge used is granular nepheline sludge, which is ground to size of less than 0.35 mm, then adding Vendian clay in amount of 15 to 20% of weight of charge and stirring until homogeneous mass is obtained, which is directed for granulation to size from 1 to 4 mm in diameter, obtained granules are dried at temperature from 100 to 110°C for at least 1 hour and fired at temperature from 600 to 700°C for not less than 1 hour.

EFFECT: obtaining a strong granulated product which enables high-efficiency treatment of waste water.

1 cl, 1 tbl, 3 ex, 2 dwg

Description

The invention relates to the field of chemical technology, in particular to a technology for producing a sorbent intended for use in the field of ecology for the purification of water bodies, in particular, it is used to purify wastewater from nickel ions by sorption.

A known method of obtaining a coagulant for the purification of natural and waste waters (RF patent No. 2195434, publ. 27.12.2002), consisting in the treatment of sludge with a mixture of carbonate and sulfate salts of alkali metals (Na ₂ CO ₃ , K ₂ CO ₃ , Na ₂ SO ₄ or their mixtures), and as a starting product for obtaining a reagent, a sludge is used, which is an intermediate product of the production of alumina, which is taken in the form of a precipitate and treated with the required volume of a 2% aqueous solution of sodium bicarbonate and sodium sulfate in a 1: 1 ratio for not less than 5 minutes, after which the resulting mixture is filtered, and the resulting precipitate is dried and ground to a powdery state.

The disadvantages of this method is the coagulating effect of the adsorbent, requiring an additional operation of water purification from reagent flakes.

There is a known method of pelletizing calcium-containing sludge and / or powder-dusty materials (RF patent No. 2527469, publ. 27.08.2014), including the preparation of starting materials for pelletizing by providing the necessary moisture, the introduction of a reagent, which is a sulfate-containing substance, which is used as sulfuric acid and / or its water-soluble salts, while the specified reagent is introduced in the amount of 0.06-0.2 grams of sulfate ion per gram of dry starting material, the components are mixed until homogeneous at a temperature of 20-60 ° C, the prepared material, and the resulting pelletized granular material is dried at a temperature of 65-170 ° C for 1-2.5 hours.

The disadvantages of this method is the complexity of the redistribution of preparing the material for granulation, namely, the need to use an additional filtering operation before granulating the material.

There is a known method of purifying wastewater from copper ions (RF patent No. 2433960, publ. 20.11.2011), including treatment with a sorbent, by filtering wastewater through a sorbent, and nepheline sludge is used as a sorbent, and the height of the sorbent layer is from 0.035 to 0.045 m.

The disadvantage of this method is the use of fine nepheline sludge, which, when compacted in a wet state, tends to condense into a monolithic waterproof material, slowing down the rate of subsequent filtration.

There is a known method of granulating fine materials (RF patent No. 2082491, publ. 06/27/1997), including the supply of moistened material to the rotating plate of the granulator, and before feeding the material to the plate, germ particles of fraction 50 - 300 μR are added to it with stirring in the amount of 25 - 30% of the volume of the material.

The disadvantages of this method are the need for strict control of the parameters of the granulator, as well as the need to introduce a large amount of seed material (up to 30% of the weight of the charge), which reduces the sorption capacity of the material.

A known method of producing an adsorbent-coagulant based on red mud (RF patent No. 2571116, publ. 20.12.2015), taken as a prototype, including acid treatment of red mud to activate it and the subsequent stages of filtration of the resulting suspension, separation of sediment, its drying and grinding, and the activation of red mud is carried out in one stage, which is carried out by washing the red mud by decantation with a 6-10 mol / l solution of hydrochloric acid (HCl) in the ratio t: w = 1: 3-5 with continuous stirring for 1 hour at room temperature to a pH level of no more than 4.

The disadvantage of this method is the high consumption of a solution of environmentally hazardous hydrochloric acid, 3-5 times higher than the mass of dry sludge material.

The technical result is to obtain a durable granular product that allows for high efficiency wastewater treatment.

The technical result is achieved by using granular nepheline sludge as a sludge, which is crushed to a particle size of less than 0.35 mm, then Vendian clay is added in an amount of 15 to 20% of the charge weight and mixed until a homogeneous charge mass is obtained, which is sent to granulation until sizes from 1 to 4 mm in diameter, the resulting granules are dried at a temperature of 100 to 110 ° C for at least 1 hour and fired at a temperature of 600 to 700 ° C for at least 1 hour.

The method is illustrated by the following figures:

fig. 1 is a graph of the dependence of the change in the concentration of nickel ions on the volume of the solution passed through the sorbent layer;

fig. 2 - graph of the dependence of the rate of passage of the solution through the sorbent on the volume of the passed solution.

The method is carried out as follows. Nepheline sludge, which is a waste of alumina production from nepheline ores, is ground in a ball mill for at least 5 minutes to a particle size of less than 0.35 mm. Clay is added to the nepheline sludge in an amount of 15 to 20% of the batch weight. Clay should have the following properties: binding capacity, sintering capacity, porosity, adsorption capacity. The resulting mixture is mixed until homogeneous for at least 1 min. Further, on a plate granulator, the charge is granulated to sizes from 1 to 4 mm in diameter. The resulting granules are dried in a drying oven at a temperature in the range from 100 to 110 ° C for at least 1 hour. Then the dried granules are fired in a muffle furnace at a temperature of 600 to 700 ° C for at least 1 hour. The resulting sorbent can be used for wastewater treatment in industrial production conditions.

The method of purifying waste water from nickel ions is illustrated by the following examples.

Example 1. A weighed sample of nepheline sludge taken from the sludge field of ZAO BaselCement-Pikalevo was ground in a ball mill for 5 minutes. Sludge with a size of less than 0.35 mm was collected using sieves. From nepheline sludge and Vendian clay, added in an amount of 17% by weight of the charge, a charge was prepared for granulation weighing 50 g. The charge was granulated in a tray granulator. The charge was placed on the plate of the granulator, while the plate was rotating, the charge was moistened with distilled water using a spray gun. The formed granules were removed from the plate manually using a spoon. It took 40 minutes to granulate the entire batch. The size of the granules obtained was from 1 to 4 mm. The moisture content of the granules obtained was 5.5-6%. The granulated sludge was dried in a drying oven at a temperature of 100-110 ° C for 1 hour. These drying conditions provide a moisture content of the granulated sludge of 0.65-0.75%. The dried granulated sludge was fired in a muffle furnace at a temperature of 500-600 ° C for 1 hour. This firing time is the minimum necessary for the clay to set. The fired pellets were left to cool in a desiccator under normal conditions.

Example 2. A weighed sample of nepheline sludge was ground in a ball mill for 5 minutes. Sludge with a size of less than 0.35 mm was collected using sieves. From nepheline sludge and Vendian clay, added in an amount of 17% by weight of the charge, a charge was prepared for granulation weighing 50 g. The charge was granulated in a tray granulator. The charge was placed on the plate of the granulator, while the plate was rotating, the charge was moistened with distilled water using a spray gun. The formed granules were removed from the plate manually using a spoon. It took 40 minutes to granulate the entire batch. The size of the granules obtained was from 1 to 4 mm. The moisture content of the granules obtained was 5.5-6%. The granulated sludge was dried in an oven at a temperature of 100-110 ° C for 1 hour. The dried granular sludge was fired in a muffle furnace at a temperature of 600-700 ° C for 1 hour. The fired granules were left to cool in a desiccator under normal conditions.

Example 3. A weighed sample of nepheline sludge was ground in a ball mill for 5 minutes. Sludge with a size of less than 0.35 mm was collected using sieves. From nepheline sludge and Vendian clay, added in an amount of 17% by weight of the charge, a charge was prepared for granulation weighing 50 g. The charge was granulated in a tray granulator. The charge was placed on the plate of the granulator, while the plate was rotating, the charge was moistened with distilled water using a spray gun. The formed granules were removed from the plate manually using a spoon. It took 40 minutes to granulate the entire batch. The size of the granules obtained was from 1 to 4 mm. The moisture content of the granules obtained was 5.5-6%. The granulated sludge was dried in a drying oven at a temperature of 105 ° C for 1 hour. The dried granular sludge was fired in a muffle furnace at a temperature of 700-800 ° C for 1 hour. The fired granules were left to cool in a desiccator under normal conditions.

The results of laboratory tests showed that granules of nepheline sludge fired at a temperature of 650 ° C are more durable than granules fired at a temperature of 550 ° C. The strength of the granules fired at 750 ° C did not increase in comparison with the strength of the granules fired at 650 ° C. Thus, the optimal firing temperature range that provides the required strength of the granular material is 600-700 ° C.

The efficiency of the obtained sorbent for purification of waste water from nickel ions has been proven by laboratory tests. In the experiment were used: state standard sample of the composition of an aqueous solution of nickel ions, 5 g / dm ³ ; distilled water; volumetric glass flask, 1000 cm ³ ; laboratory glass beakers, 100, 250, 1000 cm ³ ; analytical laboratory scales; paper filters of the "white tape"type; magnetic stirrer; atomic absorption spectrometer; laboratory tripod; glass sorption column; cotton pad; rubber tube, diameter 0.5 cm; roller clamp; plastic tubes, 15 ml.

To determine the efficiency of the obtained sorbent for the purification of waste water from nickel ions, an experiment was carried out under static conditions. Beakers with a volume of 250 ml with model solutions (100 ml of solution) and granular nepheline sludge (5 g) were installed on a magnetic stirrer, where the contents of the beakers were intensively stirred for an hour using magnets. Then the solutions were defended for 10 minutes, after which they were filtered through paper filters of the "white tape" type. The concentration of nickel ions in the model solutions after cleaning with granular belite sludge was determined by atomic absorption on an atomic absorption spectrophotometer. The cleaning efficiency was over 99%.

To determine the efficiency of the obtained sorbent for purifying wastewater from nickel ions, an experiment was carried out under dynamic conditions. A sorption column was installed in a laboratory rack, into which a cotton pad was placed and granulated nepheline sludge was poured. A 250 ml glass beaker was placed under the sorption column. The model solution was fed from a 1000 ml beaker into the sorption column through a tube; the solution flow rate was controlled by a roller clamp. The mass of sludge in the column was 5 g. The height of the sorbent layer was 0.035 m. The rate of passage of the model solution through the sorbent layer was 1 drop (0.05 ml) in 1-2 seconds. The concentration of the model solution is 10.1 mg Ni / dm ³ . The filtrate was taken into a beaker every 20 min, the volume of the passed solution was fixed. The volume of the solution passed through the sorbent layer is 2926 ml. The time interval is 11 hours 45 minutes. The experimental results are shown in Table 1.

Table 1 - Results of the experiment carried out under dynamic conditions P / p No. Time, min The volume of the passed solution, ml Ni concentration, mg / dm ³ Cleaning efficiency,% 1 20 88 0.222 97,802 2 40 160 0.0402 99.602 3 60 247 0.0071 99.93 4 80 332 0.005 99.951 five 100 415 0.005 99.951 6 120 498 0.005 99.951 7 140 578 0.005 99.951 eight 160 656 0.005 99.951 nine 180 732 0.005 99.951 ten 200 820 0.008 99.92 eleven 220 908 0.018 99.82 12 240 978 0.005 99.951 13 260 1056 0.008 99.925 fourteen 280 1140 0.012 99.885 fifteen 300 1223 0.019 99,808 sixteen 320 1309 0.024 99,767 17 340 1386 0.018 99.825 18 360 1459 0.01 99.901 nineteen 365 1478 0.005 99.95 20 385 1556 0.043 99,577 21 405 1641 0.089 99,117 22 425 1724 0.214 97.89 23 445 1809 0.453 95.514 24 465 1893 1,310 87.027 25 485 1983 2.739 72,883 26 505 2067 2.812 72,162 27 525 2148 3.358 66,757 28 545 2234 3.967 60.72 29 565 2331 5.278 47,748 thirty 585 2421 5.168 48,829 31 605 2514 5.896 41,622 32 625 2599 5.8962 41,622 33 647 2685 5.4595 45.946 34 665 2760 5.1319 49.18 35 685 2846 6.6241 34,414 36 705 2926 7.0245 30,451

The graphical dependence of the change in the concentration of nickel ions in the filtrate on the volume of the model solution passed through the sorbent layer is shown in Fig. 1.

The graphical dependence of the rate of passage of the model solution through the sorbent layer on the volume of the passed solution is shown in Fig. 2.

According to the results of the experiment, in 11 hours 45 minutes, about 3 liters of a model solution with a nickel ion concentration of 10.1 mg / dm ^{3 was} passed through a layer of 0.035 m thick granular nepheline sludge weighing 5 g. When passing the first 1.64 liters of the solution, the purification efficiency did not fall below 99.9%. A sharp drop in cleaning efficiency is observed after the 1.89 liter mark.

The rate of passage of the solution through the sorbent layer, depending on the volume of the passed solution, did not change; therefore, it is recommended to use granular belite sludge as a sorbent for wastewater treatment in industrial conditions.

The method of obtaining a sorbent for purifying wastewater from nickel ions allows obtaining a granular product, the further use of which makes it possible to increase the efficiency of purifying wastewater from nickel ions.

Claims (1)

A method of obtaining a sorbent for purifying wastewater from nickel ions, including drying and grinding sludge, characterized in that granulated nepheline sludge is used as sludge, which is crushed to a particle size of less than 0.35 mm, then Vendian clay is added in an amount of 15 to 20% of the charge weight and mixed until a homogeneous mass is obtained, which is sent for granulation to a size of 1 to 4 mm in diameter, the resulting granules are dried at a temperature of 100 to 110 ° C for at least 1 h and fired at a temperature of 600 to 700 ° C for at least 1 h.

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